Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #17 Apr 07 2020 22:14:52
%S 11,83,271,641,1259,2161,3433,51217,7297,10007,13313,172829,21977,
%T 27449,33751,40961,49139,58321,68597,800011,926111,106487,1216711,
%U 138241,156253,1757617,196831,219523,2438911,270001,297911,327689
%N Smallest nontrivial extension of n-th cube which is a prime.
%C Extensions here cannot contain leading 0's, otherwise we would have a(8)=51203. - _Sean A. Irvine_, Apr 05 2020
%H Harvey P. Dale, <a href="/A030692/b030692.txt">Table of n, a(n) for n = 1..1000</a>
%t necp[n_]:=Module[{idn=IntegerDigits[n],k=1},While[!PrimeQ[ FromDigits[ Join[ idn, IntegerDigits[k]]]],k=k+2];FromDigits[Join[idn, IntegerDigits[ k]]]]; necp/@(Range[40]^3) (* _Harvey P. Dale_, Dec 11 2013 *)
%o (PARI) a(n) = {my(k=1); while(!isprime(x=eval(concat(Str(n^3), Str(k)))), k++); x;}; \\ _Michel Marcus_, Apr 07 2020
%Y Different from A029949.
%Y Cf. A030685 (for squares).
%K nonn,base
%O 1,1
%A _Patrick De Geest_